Carnitine, one referred to as vitamin B.sub.T, is a substance participating in the metabolism of fatty acids and the DL-form thereof has heretofore been used as a stomachic. Recently, attention has been directed particularly to L-form thereof.
L-Carnitine is a substance indispensable for the transportation of fatty acids to mitochondria and is used as a therapeutic agent for heat disorders, lipemia, etc., and also as a transfusion component of hyperalimentation fluids. It is also useful as an intermediate for the production of other useful substances such as acetyl-L-carnitine.
For a long time, a chemical synthetic method has been known for the production of carnitine. However, the synthetic method is disadvantageous, from the view-points of energy consumption and environmental pollution, since it involves heating and use of mineral acids, alkalis of toxic substances and since the resulting carnitine is in the DL-form. Further, L-carnitine has heretofore been produced by optically separating DL-carnitine, obtained by the chemical synthetic method, using a diastereomer method.
Recently, various biochemical approaches have been developed for the production of L-carnitine, for example, hydroxylation of 4-N-trimethylaminobutyric acid (J. Biol. Chem., 256, 1247 (1981), reduction of 3-dehydrocarnitine (Appl. Environm. Microbiol., 39, 329 (1980)), a method using 4-chloro-3-hydroxybutyric acid ester (JP-A-59-118093 (the term "JP-A" as used herein means an "unexamined published Japanese patent application")), a method using crotonobetain as a substrate (JP-A-59-183694 and JP-A-59-118093), a method in which DL-O-acylcarnitine is hydrolyzed with an esterase (Biotechnol. Bioeng., 26, 911 (1984), etc.
These methods are disadvantageous from an industrial viewpoint since the starting materials used are expensive, the enzymes used are unstable and supply of expensive coenzymes is required. Although hydrolysis of carnitinenitrile with a mineral acid or the like has been known, biochemical hydrolysis of carnitinenitrile has not heretofore been known.
Further, to date, there have been no reports on a carnitinenitrile hydrolase which can be used in the production of intermediates for the synthesis of DL-carnitine.